1. Field of the Invention
The present invention relates to a vehicle body structure for a vehicle, such as a fuel cell vehicle, in which a fuel tank for storing a fuel gas, such as a hydrogen gas, is installed.
2. Description of the Related Art
Among automobiles, a fuel cell vehicle is known, in which electrical power is generated in a fuel cell by providing hydrogen as a fuel gas and oxygen as an oxidizing gas, and a motor is operated by the electrical power for driving the vehicle.
Among such fuel cell vehicles, a type of vehicle is known, in which a fuel tank for storing a hydrogen gas to be supplied to a fuel cell units is installed in the rear portion of the vehicle.
An example of a body structure, in which a fuel tank is supported in the rear portion of the vehicle as described above, is disclosed in Japanese Unexamined Patent Application, First Publication No. Hei 09-300987. In this supporting structure, a fuel tank storing a fuel gas (hydrogen) is mounted in a chassis frame having a rectangular frame shape while the upside of the fuel tank is directed upward, and the chassis frame supporting the fuel tank is mounted on a body frame from beneath the body frame.
According to such a structure, because the fuel tank can be easily mounted on the body frame along with suspension parts for both sides and other elements, productivity may be increased, and production cost may be reduced. In addition, by installing the fuel tank, suspension parts for both sides, and other elements on the chassis frame, the size and weight of the vehicle may be reduced.
However, in the conventional body structure described above, in order to protect the fuel tank by the chassis frame, the strength and rigidity of the chassis frame must be increased by, for example, increasing thickness of material for forming the chassis frame, or by adding reinforcements to the chassis frame, and as a result, problems are encountered in that the vehicle weight is increased, and consequently, fuel efficiency is degraded.
Another proposal has been made in Japanese Unexamined Patent Application, First Publication No. Hei 11-348815, in which an upper frame is formed so as to include a curved portion, and lower frames are configured in parallel to each other so as to absorb the energy at a rear collision; however, the performance is not satisfactory.